浅谈污水处理活性污泥法运行过程中泡沫的形成与控制

污水处理中应用活性污泥法产生生物泡沫现象会影响污水处理系统的操作、运行和出水水质,导致处理效果的降低以及运行费用的提高。本文主要讨论了活性污泥运行过程中泡沫的产生原因、影响因素、危害及控制。     

污水处理厂A^2／O工艺生物泡沫发生状况及控制

目前针对城市污水处理,应用最多的方法是活性污泥法,活性污泥法在污水处理过程中发挥着巨大的作用。但是,在活性污泥法运行过程中,时常发生两种工艺运行异常现象,即污泥膨胀和生物泡沫：关于污泥膨胀问题,很早以前就引起了污水处理专家和技术工作者的关注与研究,已经总结出污泥膨胀发生机理及解决的措施,为控制污泥膨胀提供了大量的理论和实践依据;同时,随着污水处理技术的逐渐提高,活性污泥法的新工艺不断采用（A／O、A^2/O、SBR、氧化沟等）,对污泥膨胀发生有了有效地预防;而生物泡沫问题近年来困扰着国内很多污水处理厂,生物泡沫在污水处理过程中,     

生物活性炭废水处理工艺研究

生物活性炭工艺是在活性污泥法基础上投加粉末活性炭填料共同作用的新型活性污泥法,主要应用于石化、制药等行业产生的部分难降解有毒害工业废水处理。本文通过研究发现,生物活性炭工艺的污泥驯化时间比普通活性污泥增加一倍,但污泥驯化成熟稳定后,生物活性炭工艺对废水的处理效果、耐负荷冲击能力、运行稳定性等均优于普通活性污泥工艺,另外生物活性炭工艺可有效解决普通活性污泥工艺存在污泥膨胀和生物泡沫问题。生物活性炭工艺对废水的COD_(Cr)平均去除率可达到90%,比普通活性污泥提高了10%。     

浅谈污水处理过程中泡沫的产生及其处理方法

活性污泥法运行过程中经常受泡沫问题的影响,导致处理效果的降低以及运行费用的提高。大量研究表明,污泥中某些丝状菌或放线菌的过度增殖是造成活性污泥工艺中泡沫问题的主要原因。讨论了活性污泥过程中泡沫的产生原因、已知的发泡微生物的种类、影响发泡的环境因素和过程参数及常用的泡沫控制技术,并对污泥消化过程中的泡沫问题作了简单的介绍。     

A^2／O工艺中泡沫的成因分析及控制措施

A^2／O工艺运行中曝气池活性污泥异常，出现泡沫，造成沉淀池污泥上浮是影响污水处理厂正常运行的一个棘手问题。研究表明．污泥中某些丝状菌或放线菌的过度增殖是造成活性污泥工艺中泡沫问题的主要原因，若处理不及时，会造成出水水质变差，甚至整个系统瘫痪的现象。文章以某污水厂实际运行状况，分析了两次泡沫产生的原因和采取的控制措施，以供同行参考。     

好氧活性污泥法处理过程中生物泡沫的产生与控制

好氧活性污泥法处理污水工艺较易受到生物泡沫的影响,主要原因是丝状菌的过度生长,文章对好氧活性污泥法处理过程中生物泡沫的产生原因、影响因素、控制方法等方面进行了详细的介绍和说明。     

污泥膨胀和生物泡沫的形成机理和控制方法

污泥膨胀和生物泡沫是活性污泥法在实际工程应用过程中普遍存在的问题,其主要是由于丝状菌过度繁殖。微生物种群变化和污泥沉降性能下降,以及随之出现的污泥膨胀和生物泡沫现象,会导致系统出水水质变差,运行成本提高,严重时可能会导致整个处理系统的瘫痪。文中讨论了污泥膨胀和生物泡沫产生的原因,总结了国内外污水厂污泥膨胀和发泡时常见的微生物,并对相关的控制技术进行了较为全面的综述。     

污水处理厂泡沫问题浅析

研究了在污水厂日常运行中过程中泡沫对其影响的具体表现,并对泡沫产生的原因进行了分析。初步探究了影响活性污泥法中泡沫产生的因素,进一步探讨了消除泡沫的常用方法。     

生物活性炭降解2,4-二氯酚的特性

以普通活性污泥法和石英载体生物膜法为对照，研究生物活性炭对2,4-二氯酚(2,4-DCP)的吸附特征和生物吸附动力学，探讨生物活性炭去除2,4-DCP的作用机制。结果表明：使用粉末活性炭吸附2，4-DCP可行且具有较强的抗冲击负荷能力，生物活性炭比活性污泥法、石英生物膜法的降解速率快，抗冲击负荷能力强，适合长期高浓度运行使用。     

A~2/O工艺中泡沫的成因分析及控制措施

A2/O工艺运行中曝气池活性污泥异常,出现泡沫,造成沉淀池污泥上浮是影响污水处理厂正常运行的一个棘手问题。研究表明,污泥中某些丝状菌或放线菌的过度增殖是造成活性污泥工艺中泡沫问题的主要原因,若处理不及时,会造成出水水质变差,甚至整个系统瘫痪的现象。文章以某污水厂实际运行状况,分析了两次泡沫产生的原因和采取的控制措施,以供同行参考。     

超声破乳脱水及浮渣脱水资源化利用

介绍了炼厂浮渣脱水技术的发展及超声破乳脱水领域的研究成果;综述了超声破乳脱水的优点有：在恰当的超声处理条件下能减少絮凝剂用量20％以上,浮渣超声脱水技术可加快浮渣处理速率,缩短脱水时间,超声处理5 min后浮渣含水率与沉降72 h后的效果相当,最终脱水率提高6％～7％,而且采用超声波破乳脱水技术进行浮渣破乳脱水,将脱水后浮渣应用于延迟焦化生产过程,可实现资源化利用,同时解决环保问题,获得较好的经济效益与社会效益。     

Dissolution Study of Salt of Long Chain Fatty Acids (Soap Scum) in Surfactant Solutions. Part I: Equilibrium Dissolution

Dissolution of calcium salt of a long chain fatty acid or soap scum is a major challenge for hard surface cleaners since soap scum forms when soap is exposed to hard water and has very low water solubility. In this paper, the aqueous equilibrium solubility of calcium octadecanoate (or calcium stearate) was measured as a function of pH as well as chelating agent (ethylenediaminetetraacetate disodium salt) and surfactant concentrations. Anionic, nonionic, and amphoteric surfactants were studied. The highest soap scum solubility was observed at high pH with an amphoteric surfactant. Under this condition, the chelant effectively binds calcium, and the stearate anion forms mixed micelles well with the amphoteric surfactant, which is in zwitterionic form at high pH.     

Bio-diesel production by alkali catalyzed transesterification of dairy waste scum

The potential of using dairy waste scum as a feed stock for bio-diesel production was investigated. Present study optimized the parameters involved in transesterification process of Dairy Waste Scum Oil. Gas chromatography was used to determine the fatty acid composition of Dairy Waste Scum Oil. Results revealed that the low free fatty acid content was a notorious parameter to determine the viability of alkaline transesterification. The yield of bio-diesel reached 96.7% when 1.2 wt.% of Potassium Hydroxide, reaction temperature of 75 °C, 30 min of time and 6:1 Methanol oil ratio at 350 rpm. Thermo gravimetric analysis followed the evaluation of transesterification process. The present analysis confirms that bio-diesel from dairy waste scum is quit suitable as an alternative to petroleum diesel with recommended fuel properties as per ASTM standards. This new way for using dairy waste scum reduces the cost of production of bio-diesel and the problem related to the disposal of Dairy scum.     

Design and operating experience for a fluidized bed incinerator to treat industrial hazardous scum and waste oils

The production of industrial hazardous wastes increases with population growth and industrial progress. Most industrial hazardous wastes are in the forms of sludge, scum or waste oil and have organic properties. The best way to treat those wastes is to burn them in a fluidized bed type incinerator. Because the properties of scum and waste oils are different from those of industrial sludges, the design and operation of such kinds of incinerators are also different from that for industrial sludges. This paper presents the design method and the operating experience for a fluidized bed incinerator to treat specifically industrial hazardous scum and waste oils.     

Dissolution of Soap Scum by Surfactants. Part III. Effect of Chelant Type on Equilibrium Solubility and Dissolution Rate of Calcium and Magnesium Soap Scums in Various Surfactant Systems

Soap scum can be effectively removed by using an appropriate surfactant with a chelating agent at a high solution pH. The equilibrium solubilities and dissolution rates of two model soap scums [calcium stearate and magnesium stearate: Ca(C₁₈)₂ and Mg(C₁₈)₂] were investigated in aqueous solutions containing three different types of surfactants [methyl ester sulfonate (MES) as an anionic surfactant; alcohol ethoxylate (EO9) as a nonionic surfactant; and dimethyldodecylamine oxide (DDAO) as an amphoteric surfactant] in the presence of different biodegradable chelants: trisodium ethylenediamine disuccinic acid (Na₃EDDS) and tetrasodium glutamate diacetic acid (Na₄GLDA) compared with disodium ethylenediamine tetraacetate (Na₂EDTA), a chelant with poor biodegradability. The highest equilibrium solubility and dissolution rate of either soap scum were observed at high pH in the DDAO system with Na₄GLDA. In addition, the calcium soap scum had a similar to higher equilibrium solubility and a higher dissolution rate constant as compared with the magnesium soap scum.     

Microbial conversion of sterol‐containing soybean oil production waste

Soybean extract residue (scum), a waste of soybean oil production, was examined as a raw material for C₁₇‐ketosteroid production. As a model process, its bioconversion to 9α‐hydroxyandrost‐4‐ene‐3,17‐dione (9‐OH‐AD) by Mycobacterium sp VKM Ac‐1817D was studied. The content of transformable sterols (sitosterol, stigmasterol and campesterol) in scum was estimated at ～14%. The bioconversion of scum to 9‐OH‐AD was characterized by a long lag‐period (300–350 h) followed by 9‐OH‐AD accumulation. The microbial or chemical elimination of fatty non‐identified components resulted in sterol‐enriched scum preparations. Effective conversion of these preparations by Mycobacterium sp was demonstrated: 9‐OH‐AD molar yield ～65% was reached at 60 h from the scum preparation containing 10 g dm^?3 transformable sterols. The process productivity was comparable with that for high quality‐sitosterol of wood origin (tall‐oil sitosterol). Copyright © 2004 Society of Chemical Industry     

Dissolution of Soap Scum by Surfactant. Part II: Effects of NaCl and Added Chelant on Equilibrium Solubility and Dissolution Rate of Calcium Soap Scum in Amphoteric Surfactant Solutions

The effects of solution pH and NaCl on the equilibrium solubility and dissolution rate of a model soap scum (calcium octadecanoate or calcium stearate) in aqueous solutions of dimethyldodecylamine oxide surfactant (DDAO) with and without chelant disodium ethylenediaminetetraacetate are reported. The equilibrium solubility and dissolution rate of soap scum increased with increasing solution pH when the chelant was added in the DDAO system while in the chelant-free systems the opposite trend was observed. The added NaCl has an ambiguous effect on the solubility and dissolution rate of soap scum in the absence of chelant, but a small level of added NaCl reduces both solubility and the dissolution rate constant in the presence of chelant. Both equilibrium and kinetics of dissolution are maximized at high pH with DDAO/chelant and no added salt.     

微波辐照法处理炼油厂浮渣的实验研究

针对炼油厂浮渣的性质和特点,使用微波辐照法处理炼油厂浮渣。分别考察了微波辐照功率、时间、絮凝剂用量对浮渣脱水率的影响,确定了最佳工艺条件。实验结果表明:微波辐照处理后浮渣的体积减少到原浮渣体积的30%左右,比传统方法降低了10%,实现了浮渣的减量化处理,并且节省了2/3的絮凝剂用量,大幅降低了脱出水的COD值,而且工艺简单,高效易行。     

Dissolution of Soap Scum by Surfactant Part I: Effects of Chelant and Type of Soap Scum

The equilibrium solubilities of two model soap scums [calcium stearate and magnesium stearate: Ca(C₁₈)₂ and Mg(C₁₈)₂] were measured in aqueous solutions containing three different types of surfactants: methyl ester sulfonate (MES) as an anionic; alcohol ethoxylate (EO9) as a nonionic; and dimethyldodecylamine oxide (DDAO) as an amphoteric with and without a chelating agent [disodium ethylenediaminetetraacetate (Na₂EDTA)]. The solubility of calcium soap scum was generally higher than that of magnesium soap scum, the exception being some DDAO systems. The use of the DDAO surfactant with the Na₂EDTA chelating agent at high pH gives the highest solubilities of both studied soap scums. The soap scum solubility is on the order of 2,000 times that in water at high pH. The DDAO is the most effective surfactant under all conditions. The MES is more effective than the EO9 at low pH with the opposite trend observed at high pH. The synergism from added chelant is generally greater at higher pH and is greatest for DDAO followed by EO9.